The Grenada gazette., 1887-06-11
PlATE.GLASS MAXINE =.
Methods OF Manufacture Employed in the
American Factories.

Methods OF Manufacture Employed in the
American Factories.
There are in the United States five
plate glass manufactures and another
is soon to be established at Findl ay.
O. The building or manufactory
for plate glass Is usually of very
large size. In the center is the square
melting furnace, with openings on two
parallel sides for working purposes,
while along two sides of the great
building are arranged annealing
ovens, which are sometimes thirty by
twenty feet in order to receive the inn
mense plates that are to be annealed
Two kinds of pots are used. the ordi-
nary one opens on the top, for melting
the glass, and cisterns or cuvettes. in
which the molten glass is carried to the
casting tables. In France the cuvette
Is usually of a quadrangular form.
with n groove in each of its sides, or as
in the case Of the larger cisterns, in
two parallel sides, in which the tongs
or iron-frames are fitted when the
cuvctte is moved. Between each two
parts in the furnace are placed. ac-
cording to their size, one or
more cuvettcs. In some establishments
the cuvette is not now used, the metal
being poured from the pot in which it
is melted on to the casting table. Six
teen hours is usually allowed for the
melting, and the same time for the
metal to remain in the cuvette: but
the latter term is often extended in or
der that the nriform bubbles may
escape and the excess of soda become
volatilized. Toward the last the en-
pcrature is allowed to fall, and the
glass then acquires the slight degree
of viscidity suitable for casting The
molten glass is transferred from the
pots into the adjacent cuvettcs by
means of wrought iron ladies with
long handles. When the glass is in a
proper condition to be cast, the
'tongs carriage" consisting of two
powerful bars of iron united like two
scissors blades, and resting upon two
wheels, is pushed into the opening
made in the furnace, and the cuvette
is clamped in the quadrant formed
at the extremity of the tongs, two work.
men manipulating the handles at the
other extremity. The cistcrn thus
taken from the furnace, while filled
with motion glass, is placed on an.
other carriage and quickly conveyed
to the casting table. This consists OF
a massive slab, usually of cast iron,
supported by frame. and generally
placed at the mouth OF the anneaing
oven. On each side Of the table are
ribs or bars of metal, Which keep the
glass within proper limits, and by theil
height determine the thickness of the
plate. A copper or bronze cylinder
about foot in diameter, resting upon
these bars, extends across the table.
After being heated by hot Goals placed
upon it, the table is carefully cleaned,
preparatory to casting. The cistern
containing the melted glass is raised
from the carriage on which it was
brought from the furnace by means OF
crane, its outside carefully cleaned,
and the glass skinned with n
copper sabre. The cuvette is
now swung round over the table, over
which roller covered with cloth is
drawn to remove all impurities, and
the molten glass poured out in front Of
the cylinder. which being rolled from
one extremity Of the table to the other,
spreads out the glass in sheet Of
uniform breadth and thickness. While
the plate is still red hot, about two
inches of its end is turned up like
flange, against which an iron rake-llke
instrument is placed, and the plate is
thrust forward into the annealing oven,
the temperature of which is that
of dull redness. Another plate is
now Immediately cast upon the hot
table. and the annealing oven. when
filled, is closed and left for about five
days to cool. The process for smooth
ing the glass, is rubbing the surface tc
be smoothed, with another surface
either Of glass or iron. and at the same
time applying sand or emery of differ
ent degrees of ineness. and water
between the two imping ing surfaces.-
Toledo Blade.